Selective Extraction of Copper and Aluminum from Oxidized Copper Ores

Abstract

Selective extraction of copper and aluminum from oxidized copper ores has been studied. It includes the following stages: (1) autoclave leaching of the starting material with 5% solution of (NH₄)₂SO₄; (2) separation of the soluble copper complex [Cu(NH₃)₄]²⁺ from the aluminosilicate residue; (3) mixing the moistened residue with concentrated sulfuric acid; (4) sulfatizing roasting; (5) leaching of the sulfated mass with water. During autoclave leaching, copper passes into solution in the form of a complex compound [Cu(NH₃)₄]²⁺, separating from a number of elements (Fe, Ca, Mg, Al, Si). During sulfatization, aluminosilicate minerals (feldspar, kaolin, illite and goethite) decompose and pass into the corresponding sulfate compounds. In this case, unstable sulfates, mainly iron(III) sulfate, decompose to the corresponding oxide, and aluminum remains in the form of sulfate Al(SO₄)₃. As a result of leaching of the sulfated mass with water, iron and silicon oxides remain in the residue, and aluminum passes into solution. The change in the mineralogical composition of the initial and sulfated ore mass was studied using DTA/TG, X-ray diffraction, and SEM/EDS analysis.